All five urea cycle enzymes of rat liver increased in activity 48 h after subcutaneous administration of crystalline zinc glucagon to male rats and remained elevated after 7 days of continuous glucagon infusion. The maximum ratios of enzyme activities over those of controls were 2.0 for carbamyl phosphate synthetase, 1.3 for ornithine transcarbamylase, 2.7 for argininosuccinate synthetase, 3.2 ...

The kinetic mechanism of bovine liver argininosuccinate lyase has been determined at pH 7.5, 25 degrees C. Fumarate and arginine are both noncompetitive inhibitors versus argininosuccinate. The dead-end inhibitor, succinate, is competitive versus fumarate and argininosuccinate, but noncompetitive versus arginine. Citrulline is competitive versus arginine and noncompetitive versus argininosuccin...

Key enzymes of the urea cycle and (15)N-labeling patterns of arginine (Arg) were measured to elucidate the involvement of Arg in nitrogen translocation by arbuscular mycorrhizal (AM) fungi. Mycorrhiza was established between transformed carrot (Daucus carota) roots and Glomus intraradices in two-compartment petri dishes and three ammonium levels were supplied to the compartment containing the e...

The objective of this study was to examine the effects of 6 days of emersion on nitrogen metabolism and excretion in the Chinese soft-shelled turtle, Pelodiscus sinensis. Despite having a soft shell with a cutaneous surface that is known to be water permeable, P. sinensis lost only ~2% of body mass and was able to maintain its hematocrit and plasma osmolality, [Na(+)] and [Cl(-)] during 6 days ...

In spite of recent advances in the treatment of retinoblastoma, chemotherapy is still challenging in high-stage intraocular retinoblastoma or metastatic retinoblastoma. Here, we investigated whether arginine deprivation via arginine deiminase (ADI) could be a new anti-tumor therapy in retinoblastoma cells. Expression of argininosuccinate synthetase (ASS) was detected in human retinoblastoma tis...

It has been shown that melanoma cells do not express argininosuccinate synthetase (ASS) and therefore are unable to synthesize arginine from citrulline. Depleting arginine using pegylated arginine deiminase (ADI-PEG20) results in cell death in melanoma but not normal cells. This concept was translated into clinical trial and responses were seen. However, induction of ASS expression does occur w...

Rapid determination of L-citrulline and L-arginine, physiologically important amino acids, is a beneficial technique from the scientific and medical viewpoints. In this study, enzymatic assays for L-citrulline and L-arginine were established and evaluated. L-Citrulline assay was constructed by coupling argininosuccinate synthetase to a pyrophosphate detection system, in which pyruvate phosphate...

A 40-year-old woman was admitted with altered consciousness and hyperammonemia after she had delivered her first baby. DNA analysis of the citrin gene and enzymatic assay of argininosuccinate synthetase in the liver led to a diagnosis of adult-onset type II citrullinemia (CTLN2). She was also found to have hepatocellular carcinoma (HCC) and underwent palliative surgery consisting of partial liv...

We have undertaken studies to identify amino acid residues that are involved in the catalytic mechanism of argininosuccinate synthetase [L-citrulline:L-aspartate ligase (AMP-forming), EC 6.3.4.5] and have found that a cysteine residue and an arginine residue are required for activity. The reactive cysteine residues are accessible to solvent and available to react with 5,5'-dithiobis(2-nitrobenz...